1. Field of the Invention
The present invention relates to a method for radar scanning, which switch between normal processing and emergency processing performed when it is determined that an object is in an approaching state.
2. Description of the Related Art
Radar for scanning a forward area to recognize an object has been applied to a tracking control device or collision preventing device.
A method for detecting an obstacle for a vehicle has been proposed in a device provided with such a radar. In this method, it is determined whether or not an obstacle is dangerous and when there is a risk of collision, warning is issued (JP-A-2001-126196).
A technique has been also proposed for setting a searching area and a scanning pattern according to a searching result in order for an object detection device to obtain appropriate information at all times (JP-A-2002-162469).
A technique has been also proposed for increasing a scanning speed to decrease a data updating period in a warning mode and for decreasing the scanning speed to increase the data updating period in a following mode (JP-A-Hei.11-38133).
Further, a radar device has been proposed for detecting the distance to a target by the beam scanning at a first step and for detecting the relative speed of the target by the beam scanning at a second step (JP-A-2000-9831).
Further, in order to prevent a scanning motor and a driving circuit from being excessively heated in a preceding vehicle start detecting mode, a device has been also proposed for carrying out distance measurement through scanning by measuring means at least once and for fixing a distance measuring direction when the preceding vehicle start detecting mode is set on the basis of the measurement result (JP-A-2000-46947).
Furthermore, an obstacle detecting device has been also proposed, which searches a preceding vehicle by laser scanning if there is not the preceding vehicle and causes the laser to follow the preceding vehicle when the preceding vehicle is detected so that the preceding vehicle is not lost during running a curve road (JP-A-Hei.11-160436).